Ah, I see. You are certainly right that MS DNS can be as secure as BIND, I would actually be surprised if BIND didn't actually have statistically more than MS DNS because [IIUC] MS has, over the past few years, been integrating some prover technology into their build-cycle/code-review. -- Of course since they're likely using languages that are highly resistant to analysis (the C-family as a whole) I'd take that with a grain of salt.
Don’t mistake my defense here. I believe BIND to be far superior to MSDNS. BIND allows split-horizon and ACL recursion, but MSDNS is much faster than BIND over all, as evidenced in the paper.
Also, given the prevalence of MS products in many corporate environments, MS DNS is the predominant product deployed for DNS over BIND as a whole.